Please Help Me - need input

Hi
I posted a few months ago about a pipe spoiling the look of our water feature. I have also sent this to the Hypertufa Forum because it has lots of questions about the process. But I wanted to post here too because I would like your input about the design of the 'boulder" ie: one or two pieces. .. Also I was thinking of incorporating a shallow 'bowl' into the top to make it seem like a rock with a 'natural' indentation for a bird bath (very shallow) .. but I would like some feedback on that and shape etc. etc. Any help would be appreciated. The PVC pipe is what my landscaper left me with after our water feature kept running out of water. That water feature gave him a fit. He spent a lot of time and extra manpower on it. I didn't want to insist he cover that pipe. I think it was very costly for him and he really really tried to stand behind his workmanship and fix the problem. But, dead of summer with the heat and the manpower etc., I think this was 'all he had!!" We have had a terrible drought and the landscape businesses are struggling. I empathized with that and didn't even push the issue. But I sure wish it wasn't so.....
the post in the other forum:
Originally the pipe was hidden under the bog rocks ...and then it ran underground. But the bog kept drying out and the pump would shut down because there just wasn't a big enough reservoir to accomodate the evaporation from the waterfalls etc. Anyway, now the bog --once filled to capacity with river rock and gravel - only has rocks at the surface and under those rocks is fabric and then under that there are many feet of coiled black plastic drainage pipe to fill up the large hole --but --gives lots more room for water. The bog grew to be more than double its capacity - not only deep but wide - but the pump vault remained where it was and the PVC pipe could no longer be hidden. So, I have decided to build a rock...to cover it... but it must be fairly light in comparison to a real boulder. Here are some photos. This is my first tufa project (groan).. Do you all think 1. it needs to be two 'rocks' --will one look too unnatural? 2. Regarding the recipe..I have all the ingredients (sand,cement,perlite) and I have found lots of info where some of the ingredients are omitted. No sand if you don't want weight... yes sand for fine detail...less water for moulding...etc. etc. I am thinking of leaving out the sand (weight concerns) do you think that will be ok? I have the stucco lath to give structure and also because I didn't want the mix to slide while building it. I bought the expandable foam so that I can use less cement mix (weight again) but rather use the cement/perlite as a top layer 3. Should the foam go on top or the underside of the metal lath? 4. Once the foam is ejected...do I have time to mold it in any way? 5. Will the cement/perlite mix stick to the foam? I could not find small bags of cement (my husband is here as I type saying "ask them about how much to make up...ask them about how much to make up..." SO the big question is : 6. I have the ratios of ingredients (thanks to all previous posts) but HOW much will cover this PVC pipe project...keeping in mind that I am going to form that lath mesh into a 'boulder' that is in a proportion to making it seem realistic. It's skinny (the PVC) but I bet that boulder is going to be at least 1.5 feet wide and as long as the pipe. I do think I will end up having it be two parts. One for along the bottom length and one for the vertical pipe area. 7. My last question is this: Since this is my first attempt and I have to get a feel for it all.. if I make up a small batch.. and then want to refine the mix/ratios.. can I make up more and then add to the structure? Do the materials lend to being able to build up the piece over time? Will it stick to itself if one part sets up before the other? Not knowing how much I will need (I do hope to find out from you all however) I am leaning to making up a small batch and then making more when I figure out what I will need. That will allow me to refine the ratios in case it is too thick,thin, or gloppy. Thank You all so much. Any other things/thoughts that might help? Nobody will be stepping on this at all and the bottom will likely be under water at times. Thanks so much. I will post this in several areas to get input in different aspects of the project, so you might see it more than once. Thanks again so much- Dorothy